Monaural loudness adaptation for middle-intensity middle-frequency signals: the importance of measurement technique.

Using the Simple Adaptation technique (SA) and the Ipsilateral Comparison Paradigm (ICP), the authors studied monaural loudness adaptation to a middle-intensity [60 dB(A)] tone at signal frequencies of 250, 1000, and 4000 Hz in the left and right ears. Adaptation effects were absent when the SA procedure was used. However, they were observed uniformly across all frequency values with the ICP, a result that challenges the assertion in the literature, on the basis of SA measures, that loudness adaptation for middle-intensity signals occurs only at frequencies above 4000 Hz. The ICP features periodic intensity modulations (+/-10 dB relative to the base signal) to accommodate listeners' needs for referents by which they can gauge subtle changes in the loudness of the adapting tone, a key component that is missing in the SA method. Adaptation effects in this investigation were similar in both ears, supporting the equal susceptibility assumption common in loudness adaptation studies.

Ipsilateral loudness adaptation over multiple intensity levels.

Could monaural loudness adaptation be a simple artifact of psychophysical contrast? From adaptation data based on the Ipsilateral Comparison Paradigm (ICP), A. J. Dange, J. S. Warm, E. M. Weiler, and W. N. Dember (1993) concluded that loudness adaptation was not an artifact of psychophysical contrast, but their conclusion was dependent on results from one intensity. This study, involving multiple intensities, re-examined the issue of contrast versus adaptation and generally supported the conclusions of Dange et al. The results also showed an unexpected asymmetry of adaptation based on the direction of the referent modulation used with the ICP technique. Some implications are discussed.

Abnormalities of ICP loudness adaptation at 1000 Hz associated with higher frequency (cochlear) loss.

Individuals with higher frequency hearing loss, when tested at 1000 Hz, showed more loudness adaptation at 40 dB HL and less at 60 dB HL (ISO) than the normal listeners. Adaptation was measured with the monaural method described by Weiler, Sandman and Pederson (1981), now called the Ipsilateral Comparison Paradigm (ICP) by Dange et al. (1993). Using the same method Korman (1986) had shown that a complex combination of stimulus conditions, including intensity, produced differences between a similar group with high frequency hearing loss and normals. The current results confirm the value of this method for studying adnormalities in the loudness function at middle intensities. Because it is a quick and reliable method we believe it has potential for clinical use but acknowledge considerable research and development is necessary.

Visual evoked potentials in early Alzheimer's dementia: an exploratory study.

Topographical maps of visual evoked potentials (VEPs) were recorded from 10 possible Alzheimer's disease (AD) patients and 10 control subjects. The purpose of the study was to determine if the two types of VEPs could function as a diagnostic screening for AD. Results of the statistical analysis did not reveal any latency differences between VEPs for the components elicited by either the pattern shift visual evoked potential (PSVEP)--or flash visual evoked potential (FVEP)--elicited components for AD patients compared with the control subjects; however, the information provided insight into results that are frequently lost with conventional evoked potential data. Statistically significant differences in amplitude were found between the P1 and the N2 of the PSVEP at 124, 126, and 130 ms, and at 116 ms for the FVEP.

Loudness adaptation: resolution of a psychophysical enigma.

Traditional measurement of loudness adaptation based on binaural matching has been challenged by Scharf (1983) and others as an artifact of binaural interaction due to contrast effects. Weiler, Sandman, and Pederson (1981) addressed this problem by developing a monaural technique called the ipsilateral comparison paradigm (ICP), which demonstrates strong adaptation effects within the auditory system. The two experiments described in this report support the meaningfulness of that procedure. They show that the ICP is not confounded by psychophysical contrast as suggested by Canevet, Scharf, and Botte (1983); they also demonstrate that the results obtained with the ICP are robust--adaptation effects were noted across a broad range of intensities and were similar when psychophysical reports were made by magnitude estimation and graphic rating means.

Four triggering factors in loudness adaptation.

A factor analysis was used to determine whether induced loudness adaptation (Botte, Canevet, & Scharf, 1982; Scharf, 1983) and adaptation measured by Hood's (1950) classic Simultaneous Dichotic Loudness Balance technique (SDLB) would cluster on the same factors. The two phenomena did not cluster on the same factors; thus, induced adaptation cannot replace SDLB adaptation. Four independent factors that trigger auditory adaptation were identified in the factor analysis.

Sensory alternation and vigilance performance: the role of pathway inhibition.

Posner's theory of pathway inhibition leads to the expectation that stimulus heterogeneity should attenuate the event rate effect and the decrement function in sustained attention. These predictions were tested through a sensory alternation procedure in which stimulation was shuttled between the auditory and visual modalities. Subjects detected slight reductions in the duration of recurrent flashes of light or bursts of white noise at two event rates (5 and 40 events/min) during a 50-min vigil. Consistent with the model, sensory alternation eliminated the event rate effect. It did not, however, moderate the decrement function. Although pathway inhibition can account for the effects of event rate, other factors are probably responsible for the vigilance decrement.

Redundancy: a similar principle in independent adaptation techniques.

The present study examined the similarities between four auditory adaptation techniques to determine whether the effects were correlated. The four adaptation techniques compared were: Simultaneous Dichotic Loudness Balance technique (SDLB; Hood, 1950), Magnitude Estimated Binaural technique (MEB; Botté, Canévet, & Scharf, 1982), Magnitude Estimated Monaural technique, (MEM; Weiler, Sandman, & Pederson, 1981), and the Monaural Reaction Time technique (RT; Davis & Weiler, 1976). Results did not show significant correlations between the four techniques, except (r = 0.39) between MEB and MEM procedures. This correlation was much less than the reliability of the measures would allow (r = 0.98 and r = 0.99, respectively). Thus, it appears that the different methods either produced different adaptation effects or measured different aspects of auditory adaptation. The normal ear apparently shows several forms of adaptation, which reduces the perceptual strength of a continuing stimulus, in favor of an intermittent, less redundant one.

Monaural auditory adaptation of reaction times at .5, 1, and 3 kc/s.

All procedures to measure auditory adaptation depend at least indirectly upon some subjective judgment of loudness, with the exception of the reaction-time (RT) study of Davis and Weiler (Brit. J. Audiol., 1976, 10, 102-106). We used a variant of the Davis-Weiler RT method to measure monaural adaptation at the end of tones of 7 min duration at .5, 1, and 3 kc/s at 60 db SPL, in 62 normal-hearing young adults. Adaptation was expressed as an increase in RT in msec post- vs pre-adaptation in response to a 1-sec probe tone at 10 kc/s at 70 db SPL presented simultaneously with the adapting tone, either (1) in the middle of a 2-sec burst of the adaptation tone prior to the beginning of the 7-min adaptation session (pre-adaptation measure), or (2) during the last seconds (S alerted) of the continuing adaptation tone (post-adaptation measure). Significant pre-post RT differences, collapsed over pre-post measures and over ears, were found at all 3 frequencies (p less than .0001), indicating that the Monaural Heterophonic RT (MHRT) procedure can indeed be used as an objective measure of auditory adaptation. The mean RTs across pre- and post-adaptation measures were 221.9, 217.6, and 228.0 msec in the usual frequency order, significantly different (p less than .0001). Adaptation (i.e., increased RT after 7 min of adaptation) at .5, 1, and 3 kc/s was 36.9, 28.5, and 21.6, respectively. This effect introduced a significant interaction between frequency and adaptation (p less than .001). To transfer from auditory adaptation in reduced RT in msec by the MHRT method to adaptation in reduced phons in db, it will be necessary to construct, perhaps for every S, a table of RTs for a sufficient selection of levels at the relevant frequencies.

[Physical, physiological, diagnostic and therapeutic aspects of thermography in clinical dermatology]. / Physikalische, physiologische und diagnostisch-therapeutische Aspekte der Thermographie in der klinischen Dermatologie.

Clinical application of thermovision in dermatology is a non-contact, sterile, and absolutely harmless method and offers a variety of diagnostic and therapeutical possibilities regarding the detection of irregularities in the temperature distribution of the skin. Thermovision provides us with information about the extent of dermatoses or tumors, metastases, as well as the response to therapy. Another important medical application of thermovision is dynamic testing in dermato-surgery. This technique is fundamental with regard to diagnosis, management planning, differential diagnosis, monitoring of therapeutical effects, and as a very sensitive detector of recurrence. We are going to demonstrate the applications mentioned above on the basis of a few examples.

Monaural and binaural adaptation in sequence: SDLB analogue?

Magnitude estimates (M.E.) of loudness of a 1-kc/s tone in the R ear at 60 db SPL were required over three 3-phase sessions from 15 normal-hearing young adults. The initial tone in the session was arbitrarily assigned a value of "60 units" in instructions to the S. The session was arranged to be analogous to that commonly used in Simultaneous Dichotic Loudness Balancing (SDLB). In a baseline Phase I in any of 3 sessions both ears received identical, simultaneous, intermittent stimulation. In each session, one of 3 duty cycles (randomized) were used (all on-times of .5 sec, off-times of .5, 4.5, or 24.5 sec). An M.E. judgment was requested every 10 sec for just over 1 min. Then immediately in Phase II the L ear received nothing while the R ear received continuous stimulation at 60 db SPL for 7 min, with M.E. Judgements requested every 10 sec during Min 1 and every min thereafter. Then in Phase III the R ear continued to receive continuous stimulation at 60 db SPL for 1 min while in the contralateral ear the condition of Phase I was re-introduced. M.E. loudness judgements for the R ear were requested as in Phase I. During Phase I there was, as expected, no loudness adaptation. During the adapting Phase II, M.E. group values declined progressively and significantly, but without significant differences among duty cycles. M.E. values in Phase III continued to decline significantly even though the contralateral ear was being given intermittent stimulation (irrespective of duty cycle). Previous studies had found that, for most listeners, M.E. loudness adaptation does not occur when the continuous stimulation is presented by itself. As far as is known, the present study is the first M.E. loudness adaptation study to present binaural intermittent stimulation before the continuous monaural stimulus. It is suggested that the redundancy of the continuous monaural stimulation, in comparison with the similar intermittent stimulus, is associated with the diminution of loudness.

Auditory adaptation: notes on power and parabolic curve fitting across intensity: II.

The classic Simultaneous Dichotic Loudness Balance (SDLB) procedure for the study of auditory adaptation was used by Weiler and Hood (1977) in a successful test of a model for predicting adaptation in db at intensities above the initial baseline values, using a linear approximation across levels. When Balzer et al (Brit. J. Audiol., 1984, 18, 49-50) fitted curves for simple baseline adaptation data from four studies based on SDLB data, they reported good fits for the Gompertz technique and for a parabolic formula, but did not test the relative goodness of fit for the linear formula, nor for power approximations as Stevens (1975) might have proposed. The present study makes use of the data used by Balzer et al but examines a linear fit as well as two approximations to Stevens' power law. The present finding that the linear approximation is the least efficient examined would suggest that the Weiler and Hood model should be re-examined to determine the degree to which the model can be improved by use of a curvilinear baseline fit. In addition, it might be noted that the curvilinear formulae, of necessity, involve two or more stages. It is the the current effort of this laboratory to determine whether this reflects a multifactor basis to the classic SDLB adaptation, as well as results from other adaptation techniques.

Auditory adaptation: notes on power and parabolic curve fitting across intensity and time. I.

The classic procedure for the study of auditory adaptation has been the method of Simultaneous Dichotic Loudness Balance ( SDLB ). Data from four publications ( Jerger , 1957; Palva and Karja , 1969; Weiler , Loeb and Alluisi , 1972 and Weiler and Hood, 1977) were combined to yield values extending from 20 dB to 80 dB average sensation level. A growth curve was fitted to the data by means of the Gompertz curve-fitting technique. A close fit was obtained, and a somewhat closer fit was found using a parabolic curve. In addition to the average data for SDLB adaptation across test intensities, the Gompertz method was used to fit the course of adaptation over time for one additional study ( Thwing , 1955).

Binaural phase differences and binaural auditory adaptation.

In order to determine the relationship between binaural phase localization and auditory adaptation, subjects were asked to perform a series of phase-based localization tasks, as well as an SDLB adaptation task. A binaurally presented 400 Hz tone was used for midplane localization tasks, and adaptation balances. The tone was presented monaurally during adaptation after binaural localization and the SDLB pre-test. Following 7 min exposure, subjects readjusted phase to centre the binaural stimulus in the midline, and then adjusted intensity to determine dB of adaptation. No consistent or statistically significant change in phase settings occurred. There was a significant decline in the balance intensity as a function of adaptation. A further re-establishment of the midline by phase manipulation also showed no localization effect. For the stimulus values used in the present study, there was no inter-effect of binaural phase localization, and SDLB auditory adaptation.

Vasomotor response to pure tones using photoplethysmography.

Digital photoplethysmography has been applied to the determination of hearing levels for pure tones. On average, the levels established were some 30 dB higher than those obtained with conventional pure-tone audiometry. Intervals between stimuli, however, were shown to have a significant effect upon the responses and the evidence suggests that recovery periods of 5 min may be required to obtain stable responses. The resulting testing tone involved is probably too long for most practical purposes.

Duration of increment, magnitude estimation adaptation and a proposed loudness function.

In a previous experiment on the effects of loudness adaptation on magnitude estimation (M.E.), monaural loudness adaptation was demonstrated above 30 db SL (Weiler et al, Brit. J. Audiol., 1981, 15, 210-204). Adaptation was measured by a modified method of M.E. above the loudness limit proposed by Fishkin et al (J. Ac. Soc. Am., 1977, S61). The adapting signal, a continuous pure tone, did not produce statistically significant differences in loudness M.E. for the majority of listeners. The study of Weiler et al had results similar to those of Fishkin et el, but raised questions about the comparison signal increment, since when a 20-db comparison signal was superimposed, for 5 sec out of every 30, to an ongoing signal of 60 db SPL, the subsequent judgments demonstrated an immediate and cumulative adaptation effect. The present study investigated duration effects of the comparison signal on loudness adaptation through M.E. procedures. Normal-hearing Ss (N: 10, mdn age: 24 yrs) served. The first of 3 conditions (5-sec duration of a 20-db comparison signal) showed a sizable change in M.E. for loudness, and was significantly different from conditions using 1- or 0.5-sec durations, demonstrating that a reduction in the duration of the comparison signal significantly lessened the loudness adaptation effect of the adapting signal. A discussion of the results in comparison to other studies was provided.

Magnitude estimates of loudness adaption at 60 dB SPL.

Previous reports indicate that adaptation measured by the technique of successive magnitude estimations is not found above 30 dB SL (Fishken et al., 1977; and others). Although the present study confirmed this finding at 60 dB SPL for the original procedure, it was found that a modification of the magnitude estimation procedure resulted in significant loudness adaptation at this intensity. Introduction of a 20-dB increment for 5 s, every 30 s, resulted in a marked and statistically significant decline in successive loudness judgements of the 60-dB tone. In addition, the decline in reported loudness magnitude was cumulative and progressive throughout the 7-min duration of the monaural stimulus. This is typical of classical results found with simultaneous dichotic loudness balances.